Estimation of mixing height using surface meteorological data in Thailand

Abstract

The height of the atmospheric boundary layer (ABL) or the mixing height (MH) is a key parameter of air pollution dispersion model. Two basic possibilities for the practical determination of the MH are its derivation from measurements of profile data, and its parameterization from routine meteorological data using simple models. In Thailand the radiosondes have been applied for MH only 5 stations (Bangkok, Chiang Mai, Ubonratchathani, Phuket and Songkhla station), so the MH is not normally available for the other stations. The objectives of this study to develop and apply empirical parameters that measurement in Thailand to simple model, which is used to estimate MH from surface meteorological data. The model require a few routine meteorological data of air temperature, relative humidity, wind speed and total cloud cover, and its out put is in term of hourly daytime MH and nighttime MH. The most important methods of comparison between MH obtained from model and MH obtained from upper air profile measurements had been tested on data set from Observatory for Atmospheric Radiation Research at Srisamrong, Sukhothai and data collected from Thai Meteorological Department (Bangkok, Chiang Mai, Ubonratchathani, and Phuket station) during 20 April to 6 June 2003. The results of estimation MH were tested accuracy by factor of two (FT). It found that the percentage of acceptable was about 60 – 80 %. Then, we can conclude that the simple model, which is applied the empirical parameters that measurement in Thailand can be used to estimate MH in other areas with absence of appropriate upper air sounding data.